• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.18-21
• /
• 2005

The impact of the interannual climatic variability on the vegetation sensitively appears in the timing of phenological events such as green-up, mature, and senescence. Therefore, an accurate and temporally high-resolution NDVI dataset will be required for analysis on the interannual variability of the climate-vegetation relationship. We constructed a daily 8km NDVI dataset over Eurasia based on the 8km tiled data of Pathfinder A VHRR Land (PAL) Global daily product. Cloud contamination was successfully reduced by Temporal Window Operation (TWO), which is a method to find optimized upper envelop line of the NDVI seasonal change. Based on the daily NDVI time series from 1982 to 2000, an accurate (daily) interannual change of the phenological events will be analyzed.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.5
• /
• pp.61-68
• /
• 2021

In this paper, we propose an edge computing-based exercise data collection device that can be provided for exercise rehabilitation services. In the existing cloud computing method, when the number of users increases, the throughput of the data center increases, causing a lot of delay. In this paper, we design and implement a device that measures and estimates the position of keypoints of body joints for movement information collected by a 3D camera from the user's side using edge computing and transmits them to the server. This can build a seamless information collection environment without load on the cloud system. The results of this study can be utilized in a personalized rehabilitation exercise coaching system through IoT and edge computing technologies for various users who want exercise rehabilitation.

• International Journal of CAD/CAM
• /
• v.12 no.1
• /
• pp.9-19
• /
• 2012

Generation of optimum planar B-spline curve in terms of minimum deviation and required fairness to approximate a target shape defined by a strip-shaped unorganized 2D point cloud is studied. It is proposed to use the location of control points as variables within the geometric optimization framework of point distance minimization. An adaptive simulated annealing heuristic optimization algorithm is developed to iteratively update an initial approximate curve towards the target shape. The new implementation comprises an adaptive cooling procedure in which the temperature change is adaptively dependent on the objective function evolution. It is shown that the proposed method results in an improved convergence speed when compared to the standard simulated annealing method. A couple of examples are included to show the applicability of the proposed method in the surface model reconstruction directly from point cloud data.

• Publications of The Korean Astronomical Society
• /
• v.25 no.4
• /
• pp.177-186
• /
• 2010

We developed an efficient Monte-Carlo algorithm to solve dust-scattering radiative transfer problems for continuum radiation. The method calculates the scattered intensities for various anisotropic factors ($g_i$) all at once, while actual photon packets are tracked following a scattering phase function given by a single anisotropic factor ($g_0$). The algorithm was tested by applying the method to a dust cloud embedding a star at the cloud center and found to provide accurate results within the statistical fluctuation that is intrinsic in Monte-Carlo simulations. It was found that adopting $g_0$ = 0.4 - 0.5 in the algorithm is most efficient. The method would be efficient in estimating the anisotropic factor of the interstellar dust by comparing the observed data with radiative transfer models.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.201-203
• /
• 2011

IT환경의 급격한 변화와 함께 기업들과 정부기관 그리고 개인이 만들고 수집하는 데이터양이 폭발적으로 증가하는 시기에 IT자원에 대한 유지·보수 및 관리의 부담을 줄일 수 있는 방안으로 클라우드 컴퓨팅 서비스(Cloud Computing Service)가 등장하였으며, 클라우드 컴퓨팅 서비스 환경에서 관리되는 IT 자원은 앞으로 더욱 많이 사용될 것이다. 이러한 대용량 대규모 IT자원을 효율적으로 관리하기 위해서 데이터센터는 더 많이 필요하게 될 것이다. 본 논문에서는 위와 같은 환경에서 냉방 측면에서 효율적인 데이터센터 구축 방안에 대해 알아보고 더불어 해결해야 할 과제를 제시하고자 한다.

• KIPS Transactions on Computer and Communication Systems
• /
• v.12 no.4
• /
• pp.135-142
• /
• 2023

Recently, many companies are using public cloud services or building their own data center because digital transformation is expanding. The software-defined storage is a key solution for storing data on the cloud platform and its use is expanding worldwide. Software-defined storage has the advantage of being able to virtualize and use all storage resources as a single storage device and supporting flexible scale-out. On the other hand, since the size of an object is variable, an imbalance occurs in the use of the disk and may cause a failure. In this study, a method of redistributing objects by optimizing disk weights based on storage state information was proposed to solve the imbalance problem of disk use, and the experimental results were presented. As a result of the experiment, it was confirmed that the maximum utilization rate of the disk decreased by 10% from 89% to 79%. Failures can be prevented, and more data can be stored by optimizing the use of disk.

• Journal of the Korean Institute of Gas
• /
• v.26 no.4
• /
• pp.27-35
• /
• 2022

When LPG leaks from the storage tank, the gas try to sink to the ground because LPG is heavier than air. The gas easily creates vapor clouds causing aggressive accidents in no airflow. Therefore, It is important to prevent in advance by analyzing the damaged range caused from LPG leakage and vapor clouds. So, this study analyzed the range of damaged by LPG leakage and vapor clouds with consideration of the cold air flow which is generated by the topographical characteristics and the land use status at night time in the Jeju Hagari. As a result of the cold air flow using KLAM_21, about 2 m/s of cold air was introduced in from the southeast due to the influence of the terrain. The range of damaged by LPG leakage and vapor cloud was analyzed using ALOHA. When the leak hole size is 10 cm at the wind speed of 2 m/s, the range corresponding to LEL 60 % (12,600 ppm) was 61 m which range is expected to influence in nearby residential areas. These results of this study can be used as basic data to prepare preventive measures of accidents caused by vapor cloud. Forward, it is necessary to apply CFD modeling such as FLACS to check the vapor cloud formation due to LPG leakage in a relatively narrow area and to check the cause analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.9
• /
• pp.3635-3654
• /
• 2015

With the rapid development of smart devices and mobile Internet, the video application plays an increasingly important role on mobile devices. Understanding user behavior patterns is critical for optimized operation of mobile live streaming systems. On the other hand, volume based billing models on cloud services make it easier for video service providers to scale their services as well as to reduce the waste from oversized service capacities. In this paper, the watching behaviors of a commercial mobile live streaming system are studied in a content-centric manner. Our analysis captures the intrinsic correlation existing between popularity and watching intensity of programs due to the synchronized watching behaviors with program schedule. The watching pattern is further used to estimate traffic volume generated by the program, which is useful on data volume capacity reservation and billing strategy selection in cloud services. The traffic range of programs is estimated based on a naive popularity prediction. In cross validation, the traffic ranges of around 94% of programs are successfully estimated. In high popularity programs (>20000 viewers), the overestimated traffic is less than 15% of real happened traffic when using upper bound to estimate program traffic.

• Journal of The Korean Astronomical Society
• /
• v.37 no.4
• /
• pp.137-141
• /
• 2004

We have estimated the fractal dimension of the molecular clouds in the Antigalactic Center based on the $^{12}CO$ (J = 1- 0) and $^{13}CO$ (J = 1- 0) database obtained using the 14m telescope at Taeduk Radio Astronomy Observatory. Using a developed code within IRAF, we were able to identify slice-clouds, and determined the dispersions of two spatial coordinates as well as perimeters and areas. The fractal dimension of the target region was estimated to be D = 1.34 for low resolution $^{12}CO$ (J = 1 - 0) database, and D = 1.4 for higher resolution $^{12}CO$ (J = 1 - 0) and $^{13}CO$ (J = 1 - 0) database, where $P {\propto} A^{D/2}$. The sampling rate (spatial resolution) of observed data must be an important parameter when estimating fractal dimension. Our database with higher resolution of 1 arcminute, which is corresponding to 0.2 pc at a distance of 1.1 kpc, gives us the same estimate of fractal dimension to that of local dark clouds. Fractal dimension is apparently invariant when varying the threshold temperatures applied to cloud identification. According to the dispersion pattern of longitudes and latitudes of identified slice-clouds, there is no preference of elongation direction.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.4
• /
• pp.11-16
• /
• 2015

Data center, not only the development of globally of cloud-based IT solutions, As the big data, education, use of development electronic equipment of communication means is increased, Demand of domestic and international data center has increased steadily. Due to the increase of data center demand, heat generation of server rack due to the development of IT equipment is also increasing continuously. Calculating heat value of the data center, because more than 99% of the power usage of IT server is converted into heat, the calorific value as the size and capacity of the server is larger will increase. In this paper, to center the cooling system of air-cooled, and research and development of air conditioning systems for energy reduction of data center, through performance analysis and simulation, it has been analyzed that there is energy savings.